Tropical Cyclone Sean strengthened near the coast of Western Australia on Saturday. At 10:00 p.m. EST on Saturday the center of Tropical Cyclone Sean was located at latitude 19.7°S and longitude 115.7°E which put the center about 120 miles (195 km) northwest of Karratha, Australia. Sean was moving toward the west-southwest at 14 m.p.h. (22 km/h). The maximum sustained wind speed was 60 m.p.h. (95 km/h) and there were wind gusts to 75 m.p.h. (120 km/h). The minimum surface pressure was 987 mb.
A Warning was in effect for the portion of the coast from Whim Creek to Ningaloo. The Warning included Karratha, Damoier, Onslow, and Exmouth.
A former Tropical Low near the coast of Western Australia strengthened on Saturday and the Australian Bureau of Meteorology designated the system as Tropical Cyclone Sean. The inner end of a rainband wrapped around the western side of the center of Tropical Cyclone Sean. A circular eye appeared to be forming at the center of Sean’s circulation. Bands of showers and thunderstorms were revolving around the center of Tropical Cyclone Sean. Storms near the center of Sean generated upper level divergence that pumped mass away from the tropical cyclone. The removal of mass allowed the surface pressure to decrease.
The distribution of wind speeds around Tropical Cyclone Sean was relatively symmetrical. Winds to tropical storm force extended out 115 miles (185 km) from the center of Sean’s circulation.
Tropical Cyclone Sean will move through an environment favorable for intensification during the next 24 hours. Sean will move over water where where the Sea Surface Temperatures are near 30°C. It will move under the northern part of an upper level ridge northwest of Australia. The upper level ridge will produce easterly winds are that will blow toward the top of Sean’s circulation. Those winds will cause some vertical wind shear. The wind shear will inhibit intensification, but the shear will not be enough to prevent intensification. Tropical Cyclone Sean will to intensify during the next 24 hours. Sean could strengthen to the equivalent of a hurricane/typhoon.
Tropical Cyclone Sean will move around the northwestern part of a high pressure system over Australia. The high pressure system will steer Sean toward the west-southwest during the next 24 hours. On its anticipated track, Tropical Cyclone Sean will move parallel to the coast of Western Australia. The center of Sean is forecast to remain over water.
Bands in the southern side of Tropical Cyclone Sea will bring gusty winds and locally heavy rain to the coast of Western Australia. Heavy rain could cause flash floods in some locations.